Gavin Linsley-Noakes - Academia.edu (original) (raw)

Uploads

Papers by Gavin Linsley-Noakes

Research paper thumbnail of Effects of winter temperatures on flower development in two clones of kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson)

Scientia Horticulturae, 1987

Linsley-Noakes, G. C. and Allan, P., 1987. Effects of winter temperatures on flower development i... more Linsley-Noakes, G. C. and Allan, P., 1987. Effects of winter temperatures on flower development in two clones of kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson). Scientia Hortic., 33: 249-260. Winter temperature has a dramatic effect on flowering in kiwifruit. The clone 'Hayward' has a significantly higher chilling requirement than 'Allison'. Flowering in both clones increased with increasing winter chilling. At Greytown, the coldest of three locations, where 872 h below 7.2 ° C (1354 Richardson units) were recorded, 400 'Allison' and 154 'Hayward' flowers were produced per 100 buds. At Kranskop, a climatically marginal location with 624 h below 7.2°C (959 Richardson units), 243 'Allison' and 2 'Hayward' flowers were produced per 100 buds. The warmest winter, with only 212 h below 7.2 °C (222 Richardson units), was at Pietermaritzburg, where 35 'Allison' flowers per 100 buds and no 'Hayward' flowers were recorded. Increased chilling increased the reproductive budbreak percentage, the number of flowering nodes per flowering shoot and also the number of flowers per node. Seven stages were determined in the development of flower primordia. Stage III was reached in both cultivars in all three areas by autumn, but where inadequate chilling and high winter day temperatures occurred, further development was delayed during winter/spring and flower parts did not differentiate. Flower primordia that failed to differentiate, or aborted soon afterwards, ceased to function. Vegetative development from these positions, after the original buds had developed shoots on which each primordium became a bud, was from adventitious buds arising at the bases of the primordia. Where chilling requirements were satisfied, normal flower differentiation occurred in spring. Most flowers were formed around the fourth and fifth leaf primordia within 'Allison' and 'Hayward' buds, respectively.

Research paper thumbnail of Temperature as a factor in nectarine production in the Western Cape

1.4 DISCUSSION AND CONCLUSION CHAPTER TWO: COMPARISON OF REST COMPLETION PREDICTION MODELS FOR NE... more 1.4 DISCUSSION AND CONCLUSION CHAPTER TWO: COMPARISON OF REST COMPLETION PREDICTION MODELS FOR NECTARINES 2.1 INTRODUCTION 2.2 MATERIALS AND METHODS 2.3 RESULTS 2.3.1 1988 Season 2.3.2 1989 Season 2.3.3 1990 Season 2.3.4 Overall trends and statistical analyses 2.4 DISCUSSION AND CONCLUSION CHAPTER THREE: DEVELOPMENT OF A REST COMPLETION PREDICTION MODEL FOR WESTERN CAPE CLIMATIC CONDITIONS 3.1 INTRODUCTION 3.2 MATERIALS AND METHODS 3.3 RESULTS 3.3 .1 1988 Season 3.3.2 1989 Season 3.3.3 1990 Season i i i 3.3.4 Overall trends and statistical analyses 43 3.4 DISCUSSION AND CONCLUSION 46 CHAPTER FOUR: EFFECT OF HEAT UNIT ACCUMULATION IN 51 WINTER AND SPRING ON ENDODORMANCY AND FLOWERING DATES 4.1 INTRODUCTION 4.2 MATERIALS AND METHODS 4.3 RESULTS 4.3.1 1988 Season 4.3.2 1989 Season 4.3.3 1990 Season 4.3.4 Overall trends and statistical analyses 4.3.5 Field bud break data 4.3.6 Interaction of heat and chilling during dormancy 4.4 DISCUSSION AND CONCLUSION

Research paper thumbnail of Improving flowering of kiwifruit in climatically marginal areas using hydrogen cyanamide

Scientia Horticulturae, 1989

Application of hydrogen cyanamide (H2NC-= N; Dormex®) more than doubled the average flowering int... more Application of hydrogen cyanamide (H2NC-= N; Dormex®) more than doubled the average flowering intensity when applied to 8 kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Laing et A.R. Ferguson) orchards in the Western Cape. All pollinated flowers set fruit and this represented a potential doubling of production. There appeared to be some interaction between concentration and application time. Concentration had a much greater influence than application time. Three and 4% hydrogen cyanamide gave the highest flowering intensities. Application 5, 4 or 3 weeks before natural bud break gave equally good results, however, the vines showed increasing sensitivity to hydrogen cyanamide with decreasing time to bud break. The increased flowering intensity was brought about mainly by a more compact bud break period, which increased the proportion of flower-bearing (reproductive) shoots, as well as by an increase in the number of flowers on individual shoots. Overall bud break percentages were increased as well, but this had a smaller influence than the altered flower development pattern. The low chilling cultivar 'Abbott' was more sensitive to the chemical than cultivar 'Hayward' and showed phytotoxicity at the higher concentration (4%). The mature vines were naturally more productive, but showed a lower response to hydrogen cyanamide than the young vines. Mature vines generally had higher average flower numbers per reproductive shoot. The response to hydrogen cyanamide appeared to be greater in the orchards that received higher winter chilling accumulation.

Research paper thumbnail of Cultivar and planting date effects on the growth, yield and quality of strawberries in the Western Cape, South Africa

South African Journal of Plant and Soil, 2021

In South Africa, strawberry Fragaria × ananassa (Duchesne ex Weston) Duchesne ex Rozier growers h... more In South Africa, strawberry Fragaria × ananassa (Duchesne ex Weston) Duchesne ex Rozier growers have not been able to extend the growing season and produce strawberries year-round primarily due to the types of cultivar available and climatic limitations. The objective of the study was to determine the effects of planting date- and day-neutral strawberry varieties on plant growth, yield and quality in the south-eastern region of the Western Cape. The experiment was conducted as a split-plot design with three replications. Planting dates were the whole plot treatments, while varieties constituted the sub-plot treatments. The sub-plot treatments were laid out in a randomised complete block design. Three day-neutral strawberry varieties, ‘Monterey’, ‘San Andreas’ and ‘Albion’ were planted at 30-day intervals from April to September for the 2018/2019 season in standard coir grow-bags at a density of 75 000 ha−1. ‘Monterey’ significantly outperformed ‘San Andreas’ which in turn significantly (p < 0.05) outperformed ‘Albion’ for crown number, flower number, yield and fruit size. ‘San Andreas’ produced significantly fewer runners than ‘Monterey’ and ‘Albion’. ‘Albion’ produced significantly higher total soluble solids followed by ‘Monterey’ and ‘San Andreas’. It was concluded that ‘Monterey’ planted in April and ‘San Andreas’ planted in August, can be used to extend the harvest season.

Research paper thumbnail of Effects of winter temperatures on flower development in two clones of kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson)

Scientia Horticulturae, 1987

Linsley-Noakes, G. C. and Allan, P., 1987. Effects of winter temperatures on flower development i... more Linsley-Noakes, G. C. and Allan, P., 1987. Effects of winter temperatures on flower development in two clones of kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson). Scientia Hortic., 33: 249-260. Winter temperature has a dramatic effect on flowering in kiwifruit. The clone 'Hayward' has a significantly higher chilling requirement than 'Allison'. Flowering in both clones increased with increasing winter chilling. At Greytown, the coldest of three locations, where 872 h below 7.2 ° C (1354 Richardson units) were recorded, 400 'Allison' and 154 'Hayward' flowers were produced per 100 buds. At Kranskop, a climatically marginal location with 624 h below 7.2°C (959 Richardson units), 243 'Allison' and 2 'Hayward' flowers were produced per 100 buds. The warmest winter, with only 212 h below 7.2 °C (222 Richardson units), was at Pietermaritzburg, where 35 'Allison' flowers per 100 buds and no 'Hayward' flowers were recorded. Increased chilling increased the reproductive budbreak percentage, the number of flowering nodes per flowering shoot and also the number of flowers per node. Seven stages were determined in the development of flower primordia. Stage III was reached in both cultivars in all three areas by autumn, but where inadequate chilling and high winter day temperatures occurred, further development was delayed during winter/spring and flower parts did not differentiate. Flower primordia that failed to differentiate, or aborted soon afterwards, ceased to function. Vegetative development from these positions, after the original buds had developed shoots on which each primordium became a bud, was from adventitious buds arising at the bases of the primordia. Where chilling requirements were satisfied, normal flower differentiation occurred in spring. Most flowers were formed around the fourth and fifth leaf primordia within 'Allison' and 'Hayward' buds, respectively.

Research paper thumbnail of Temperature as a factor in nectarine production in the Western Cape

1.4 DISCUSSION AND CONCLUSION CHAPTER TWO: COMPARISON OF REST COMPLETION PREDICTION MODELS FOR NE... more 1.4 DISCUSSION AND CONCLUSION CHAPTER TWO: COMPARISON OF REST COMPLETION PREDICTION MODELS FOR NECTARINES 2.1 INTRODUCTION 2.2 MATERIALS AND METHODS 2.3 RESULTS 2.3.1 1988 Season 2.3.2 1989 Season 2.3.3 1990 Season 2.3.4 Overall trends and statistical analyses 2.4 DISCUSSION AND CONCLUSION CHAPTER THREE: DEVELOPMENT OF A REST COMPLETION PREDICTION MODEL FOR WESTERN CAPE CLIMATIC CONDITIONS 3.1 INTRODUCTION 3.2 MATERIALS AND METHODS 3.3 RESULTS 3.3 .1 1988 Season 3.3.2 1989 Season 3.3.3 1990 Season i i i 3.3.4 Overall trends and statistical analyses 43 3.4 DISCUSSION AND CONCLUSION 46 CHAPTER FOUR: EFFECT OF HEAT UNIT ACCUMULATION IN 51 WINTER AND SPRING ON ENDODORMANCY AND FLOWERING DATES 4.1 INTRODUCTION 4.2 MATERIALS AND METHODS 4.3 RESULTS 4.3.1 1988 Season 4.3.2 1989 Season 4.3.3 1990 Season 4.3.4 Overall trends and statistical analyses 4.3.5 Field bud break data 4.3.6 Interaction of heat and chilling during dormancy 4.4 DISCUSSION AND CONCLUSION

Research paper thumbnail of Improving flowering of kiwifruit in climatically marginal areas using hydrogen cyanamide

Scientia Horticulturae, 1989

Application of hydrogen cyanamide (H2NC-= N; Dormex®) more than doubled the average flowering int... more Application of hydrogen cyanamide (H2NC-= N; Dormex®) more than doubled the average flowering intensity when applied to 8 kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Laing et A.R. Ferguson) orchards in the Western Cape. All pollinated flowers set fruit and this represented a potential doubling of production. There appeared to be some interaction between concentration and application time. Concentration had a much greater influence than application time. Three and 4% hydrogen cyanamide gave the highest flowering intensities. Application 5, 4 or 3 weeks before natural bud break gave equally good results, however, the vines showed increasing sensitivity to hydrogen cyanamide with decreasing time to bud break. The increased flowering intensity was brought about mainly by a more compact bud break period, which increased the proportion of flower-bearing (reproductive) shoots, as well as by an increase in the number of flowers on individual shoots. Overall bud break percentages were increased as well, but this had a smaller influence than the altered flower development pattern. The low chilling cultivar 'Abbott' was more sensitive to the chemical than cultivar 'Hayward' and showed phytotoxicity at the higher concentration (4%). The mature vines were naturally more productive, but showed a lower response to hydrogen cyanamide than the young vines. Mature vines generally had higher average flower numbers per reproductive shoot. The response to hydrogen cyanamide appeared to be greater in the orchards that received higher winter chilling accumulation.

Research paper thumbnail of Cultivar and planting date effects on the growth, yield and quality of strawberries in the Western Cape, South Africa

South African Journal of Plant and Soil, 2021

In South Africa, strawberry Fragaria × ananassa (Duchesne ex Weston) Duchesne ex Rozier growers h... more In South Africa, strawberry Fragaria × ananassa (Duchesne ex Weston) Duchesne ex Rozier growers have not been able to extend the growing season and produce strawberries year-round primarily due to the types of cultivar available and climatic limitations. The objective of the study was to determine the effects of planting date- and day-neutral strawberry varieties on plant growth, yield and quality in the south-eastern region of the Western Cape. The experiment was conducted as a split-plot design with three replications. Planting dates were the whole plot treatments, while varieties constituted the sub-plot treatments. The sub-plot treatments were laid out in a randomised complete block design. Three day-neutral strawberry varieties, ‘Monterey’, ‘San Andreas’ and ‘Albion’ were planted at 30-day intervals from April to September for the 2018/2019 season in standard coir grow-bags at a density of 75 000 ha−1. ‘Monterey’ significantly outperformed ‘San Andreas’ which in turn significantly (p < 0.05) outperformed ‘Albion’ for crown number, flower number, yield and fruit size. ‘San Andreas’ produced significantly fewer runners than ‘Monterey’ and ‘Albion’. ‘Albion’ produced significantly higher total soluble solids followed by ‘Monterey’ and ‘San Andreas’. It was concluded that ‘Monterey’ planted in April and ‘San Andreas’ planted in August, can be used to extend the harvest season.